CVE-2026-85818 Windows Schannel Spoofing Vulnerability

Critical 9.0 Published 13 Oct 2026 Updated 29 Oct 2026

An attacker can bypass cryptographic signature verification in Windows Schannel to perform network spoofing, requiring immediate patching.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-85818?

CVE-2026-85818 is a critical vulnerability in Microsoft Windows 11 23h2, published on 13 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Improper verification of cryptographic signature in Windows Schannel allows an unauthorized attacker to perform spoofing over a network.

Weakness: CWE-347

Which versions are affected by CVE-2026-85818?

It affects 7 products.

Products include Microsoft Windows 11 23h2, Microsoft Windows 11 24h2, Microsoft Windows 11 25h2, Microsoft Windows 11 26h1, Microsoft Windows 11 26h2, Microsoft Windows Server 2022 and 1 more.

How do I fix CVE-2026-85818?

No fix has been published for CVE-2026-85818 yet. Limit exposure of the affected software until one is available.

Is CVE-2026-85818 being exploited?

There is no known exploitation of CVE-2026-85818 in the wild and no public exploit code.

All Microsoft Windows 11 23h2 vulnerabilities

Sources

Also known as GHSA-7j3q-9qpw-gwc7.